Conventional aircraft AUTOBRAKE systems may control airplane deceleration to one of several predetermined aircraft deceleration settings. Thus, if a pilot wishes to stop the airplane at a certain point on the runway, for example at a runway exit, it may be unlikely that the AUTOBRAKE system would provide a deceleration setting that matches the stopping distance to the selected runway stop point. The pilot's choice may be to select one of the deceleration settings, and, if the airplane decelerates too quickly, the pilot may select another AUTOBRAKE setting or disarm the AUTOBRAKE system and use pedal braking to avoid stopping short of the desired point. If, however, the airplane decelerates too slowly, the pilot may again need to revert to a different AUTOBRAKE setting or to pedal braking to increase deceleration to stop the airplane at the selected stopping point. Both of the above conditions may result in uneven deceleration that may be apparent to the airplane passengers.
Aircraft AUTOBRAKING systems have been developed which apply predetermined braking to an aircraft. These AUTOBRAKING systems may provide four or five selectable deceleration rates which can be used to decelerate the landing aircraft at the deceleration rate selected by the pilot. The result may be either the braking of the aircraft at a specific rate until stopped or the pilot taking command of braking before the aircraft stops.
Modern aircraft may have the ability to determine aircraft position on the runway, calculate the deceleration rate of the aircraft for a specific exit taxiway on that runway, and automatically modulate the application of the aircraft brakes such that the aircraft arrives at the exit taxiway at a speed slow enough as to exit at the predefined exit taxiway. An optimum runway exiting (ORE) system currently in use may enable pilots to specify target landing runway taxiway exits for vacating landing runways and provides predicted landing performance targets. Currently, this predicted landing performance may be based on use of either the MAX Reverse setting or the IDLE Reverse setting on the reverse thrust system of the engines. These may be the only two reverse thrust detent positions which are available for braking of the aircraft upon landing and for which landing performance data can be produced. In some applications, however, use of only the MAX Reverse setting or the IDLE Reverse setting may provide insufficient landing performance resolution or non-optimum performance.